A cooling-storage type heat exchanger is already known in the art, for example, as disclosed in Japanese Patent Publication No 2011-012947 (A). The heat exchanger of this kind is composed of multiple refrigerant tubes, which extend in a vertical direction and form refrigerant passages therein, and multiple cooling-storage containers arranged between neighboring refrigerant tubes.
In the above heat exchanger, convex portions and concave portions are formed in side plates of the cooling-storage container and they are alternately arranged in the vertical direction. The cooling-storage containers are fixed to the refrigerant tubes at the convex portions, which are formed at equal pitches in the vertical direction. The cooling-storage container is separated from the refrigerant tubes at the concave portions to form air passages, through which outside air (which cools down, for example, a passenger compartment of a vehicle) in a cold-energy storing operation or a cold-energy discharging operation. In the cold-energy storing operation, liquid-phase refrigerant flowing through the refrigerant passages is vaporized so that heat is absorbed from the outside air and cooling-storage material contained in the respective cooling-storage containers. In the cold-energy discharging operation, the cold-energy stored in the cooling-storage material is discharged to the outside air passing through the heat exchanger. The air passages, which are formed between the refrigerant tubes and the concave portions, are also used as a space for discharging condensed water, which is generated in the cold-energy storing operation for the cooling-storage material.
In the above heat exchanger, the condensed water is likely to remain in a lower portion thereof, when the condensed water is generated in the cold-energy storing operation for the cooling-storage material and the condensed water flows in a downward direction (in a gravity direction). In addition, the condensed water may not be easily discharged from the air passages formed between refrigerant tubes and the concave portions of the cooling-storage containers, and thereby the condensed water may be filled therein to cover the air passages. In addition, the refrigerant, which flows through the refrigerant passages, are likely to stay in the gravity direction (that is, in a lower portion of the refrigerant passage in the vertical direction). Therefore, temperature of the refrigerant tubes in a lower portion is likely to become lower than that in an upper portion of the refrigerant tubes.
Accordingly, when the condensed water remains in the air passages between the refrigerant tubes and the cooling-storage containers in the lower portion thereof, the condensed water will be easily frozen. Then, it may cause a disadvantage that the heat exchanger may be deformed due to cubical expansion generated by the freeze of the condensed water.